1. Field of the Invention
The present invention relates to a method and a system for the automatic optical inspection of a tread profile of at least one wheel of a vehicle, especially with regard to suitability of the tread profile for winter road conditions.
2. Description of the Related Art
Methods for ascertaining the tread depth of a vehicle tire are known from the related art. These methods are usually based on triangulation or light section methods, by which the tread depth of the tire can be ascertained in at least one or more examined section(s) of the tire.
Published German patent application document DE 10 2009 016 498 A1 describes such a method, in which a section of a tire tread is irradiated in its width direction from a position below the road surface using a line-type light beam, usually laser light, and the reflection of the light beam is detected by a sensor, e.g., a camera providing two-dimensional resolution, which is likewise disposed underneath the road surface. From the image thus recorded, and with the aid of a triangulation method, it is possible to ascertain a tread depth; the method is also able to be used on multiple sections of the tire, so that information regarding the tread depth distributed across the tire can be obtained.
Published German patent application document DE 195 15 949 C2 describes a method for the surface measuring and recording of tread wear of a tire tread, in which the wheel, i.e., the tire and wheel rim, is measured separately from the vehicle. Here, too, the tire tread is illuminated by a linear or strip-type light beam and the reflection recorded by a video camera. Via a gray scale analysis or a phase shift method, the profile wear of the tread can be determined.